Method for purifying (meth) acrylate

Abstract

The invention relates to the field of separation, and discloses a refining method of (methyl) acrylate. The method comprises the steps that a (methyl) acrylate sample and an extraction agent are mixed, extraction and phase splitting are carried out, a light phase and a heavy phase containing phenolic compounds are obtained, and the extraction agent contains at least one of C1-C12 monohydric alcohols; or the extracting agent is at least one of polyhydric alcohols with the melting point being less than 40 DEG C. The method is high in extraction efficiency, phenolic compounds in (methyl) acrylate can be better removed, and emission of three wastes can be greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of separation, and more specifically to a method for purifying (meth)acrylates. Background Technology

[0002] (Meth)acrylates are commonly used chemical raw materials and products, widely applied in polymers, lubricants, mechanical lubrication, and many other fields. Phenols, as commonly used polymerization inhibitors, antioxidants, and byproducts of some raw materials, inevitably end up in ester compound products. In many application areas, such as food processing, polymerization reactions, and aquatic environments, (meth)acrylate products typically have strict limits on phenol content, necessitating phenol removal purification. For example, phenolic compounds are added as polymerization inhibitors in the production of unsaturated fatty acid esters (such as acrylates and methacrylates). However, when these ester compounds are used as monomer raw materials in polymerization reactions, phenol removal is necessary; otherwise, it will adversely affect the polymerization reaction.

[0003] Currently, the commonly used method for removing phenols in the production of (meth)acrylate compounds is alkaline washing. Alkaline washing has the advantages of simple operation and low cost, but it produces a large amount of strong alkaline solution containing phenol. This type of wastewater has poor biodegradability and is extremely difficult to treat. At the same time, emulsification is very likely to occur during alkaline washing, which can easily lead to a decrease in product yield.

[0004] In the field of separating phenolic compounds from coal tar, methods such as complexation, supercritical fluid extraction, and ionic liquid extraction have achieved certain results. However, complexation often involves solid raw materials, and the particle size of these materials limits its continuous production. CN108211423A provides a method for using a biodegradable compound as an adsorbent to adsorb and separate phenolic compounds from oil, and for regenerating the adsorbent. This method involves adding a certain amount of biodegradable adsorbent to an oil-phenol mixture, stirring at a certain temperature, and selectively adsorbing the phenolic compounds in the mixture due to acid-base interaction. The adsorbent then separates the phenolic compounds from the oil phase through filtration. A desorbent is then added to the filtered adsorbent containing phenolic compounds, dissolving the phenolic compounds in the desorbent. The adsorbent is then separated by filtration and reused. The phenolic compounds in the desorbent are recovered by distillation, and the desorbent is reused. This method is essentially a complexation method, but it is environmentally friendly.

[0005] Solvent extraction for phenol removal primarily uses ketones as the main extractant to extract phenolic compounds from wastewater, and is widely used in the treatment of phenol-containing wastewater, but its application in the removal of phenols from organic matter is limited. CN105712427A discloses an extractant and extraction method with a high partition coefficient for phenol-containing wastewater, using methyl isobutyl ketone as the main extractant and toluene as a synergistic extractant to form a composite extractant, which significantly improves the extraction effect on polyphenols. However, solvent extraction methods for phenolic compounds in wastewater are not suitable for ester compounds. Supercritical fluid extraction and ionic liquid extraction are limited in their application due to equipment limitations and the high cost and scarcity of extractants.

[0006] Therefore, there is still a need to develop environmentally friendly methods for the removal of phenolic compounds from organic matter, while also ensuring that these methods have a good removal rate and reduce the complexity of post-treatment. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and provide a method for refining (meth)acrylates. This method has high extraction efficiency, can better remove phenolic compounds from (meth)acrylates, the extractant can be recycled, and the emission of waste gas, wastewater, and solid waste can be significantly reduced.

[0008] To achieve the above objectives, the present invention provides a method for purifying (meth)acrylates, the method comprising: mixing a (meth)acrylate sample with an extractant, extracting, and separating the phases to obtain a light phase and a heavy phase containing phenolic compounds;

[0009] The extractant contains at least one of C1-C12 monohydric alcohols; or, the extractant contains at least one of polyhydric alcohols with a melting point less than 40°C.

[0010] The method provided by this invention can effectively remove phenolic compounds from (meth)acrylate samples, achieving high extraction efficiency, recyclable extractant, and a high yield of (meth)acrylate. Lower alcohols are easily separated and inexpensive, while polyols are highly polar and environmentally friendly. This method is particularly suitable for removing phenolic compounds from (meth)acrylate samples, and it is relatively simple to operate, low in cost, and has broad application prospects. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] In this invention, "(meth)acrylate" refers to acrylates and / or methacrylates.

[0013] The present invention provides a method for purifying (meth)acrylates, the method comprising: mixing a (meth)acrylate sample with an extractant, extracting, and separating the phases to obtain a light phase and a heavy phase containing phenolic compounds;

[0014] The extractant contains at least one of C1-C12 monohydric alcohols; or, the extractant contains at least one of polyhydric alcohols with a melting point less than 40°C.

[0015] Polyols refer to alcohols with two or more units, including polyols in polymer form.

[0016] The inventors of this invention discovered during their research that, when the extractant is as described above, it is possible to ensure the complete removal of phenolic compounds from the (meth)acrylate sample through a single extraction operation. After phase separation, the methacrylate enters the lighter phase (upper layer). The resulting heavier phase can be recovered by vacuum distillation to recycle the extractant. During extraction, the (meth)acrylate sample is in a liquid state.

[0017] According to the present invention, preferably, in the (meth)acrylate sample, the number of carbon atoms in the structure derived from the alcohol is 1-20, more preferably 4-18 (e.g., 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18). It is understood that esters are reaction products of acids and alcohols, and their structures include structures derived from both acids and alcohols. For example, (meth)acrylates can be methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, etc.

[0018] According to the present invention, preferably, the content of phenolic compounds in the (meth)acrylate sample is 5-9000 mg / kg, more preferably 50-4000 mg / kg, and even more preferably 500-4000 mg / kg (for example, it can be 500, 800, 1000, 1200, 1500, 1800, 2000, 2500, 3000, 3500, 4000, and values ​​within any two of the above values) mg / kg. The method of the present invention is more applicable to the above conditions. The above "mg / kg" refers to the mass (mg) of phenolic compounds per kg of (meth)acrylate sample. According to a preferred embodiment of the present invention, the (meth)acrylate sample mainly contains (meth)acrylate and phenol.

[0019] According to the present invention, the phenol is mainly derived from the polymerization inhibitor added during the preparation of (meth)acrylate, and the phenol is selected from monohydric phenols and / or polyhydric phenols. Polyhydric phenols refer to phenols with a di- or higher number of phenols.

[0020] According to the present invention, preferably, the phenol is selected from at least one of phenol, cresol, ethylphenol, dimethylphenol, 2,6-di-tert-butyl-p-cresol, naphthol, hydroquinone, and resorcinol.

[0021] According to the present invention, preferably, the mass ratio of (meth)acrylate sample to extractant is 1:(0.3-10), more preferably 1:(0.5-3). This further ensures the complete extraction of phenolic compounds.

[0022] According to the present invention, preferably, the extraction conditions include: a temperature of 0-90°C, more preferably 20-80°C (for example, it can be 20, 22, 25, 28, 30, 32, 35, 38, 40, 45, 50, 60, 70, 80 and any two of the above values)°C, and more preferably 30-60°C.

[0023] According to the present invention, preferably, the extractant is a polyol with a melting point of less than 35°C.

[0024] According to the present invention, preferably, the polyol is selected from at least one of tetraethylene glycol (melting point -6°C), ethylene glycol (melting point -13°C), glycerol (melting point -20°C), and polyethylene glycol (melting point less than 30°C). The weight-average molecular weight of the polyethylene glycol can be 200-1000 g / mol (e.g., 200, 300, 400, 500, 600, 700, 800, and values ​​within any two of the above values). The polyethylene glycol is preferably at least one of polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, and polyethylene glycol 600. Taking polyethylene glycol 200 as an example, 200 refers to its weight-average molecular weight of 200 g / mol.

[0025] According to the present invention, preferably, the extractant further includes one or two of 1,2,4-triazole and water-soluble imidazoline.

[0026] According to the present invention, preferably, the mass content of the 1,2,4-triazole and / or water-soluble imidazoline is 2-10 wt%, based on the total mass of the extractant.

[0027] Under the above conditions, it is possible to further ensure the complete removal of phenolic compounds.

[0028] According to the present invention, preferably, the monohydric alcohol is selected from C1-C8 monohydric alcohols, and more preferably at least one of methanol, ethanol, propanol, butanol, pentanol and hexanol.

[0029] According to the present invention, preferably, the extractant is a mixture of C1-C12 monohydric alcohol and water.

[0030] According to the present invention, preferably, the mass ratio of the monohydric alcohol to water is (0.5-9):1, more preferably (0.5-2.3):1. For example, it can be a methanol-water mixture with a mass ratio of (2-3):1.

[0031] The monohydric alcohol mentioned therein can be a mixture of C1-C12 monohydric alcohols. The present invention does not impose a particular limitation on the specific proportion of such a mixture, and phenolic compounds can be sufficiently removed at any proportion. For example, the extractant can be a mixture of ethanol and n-hexanol, with a mass ratio of n-hexanol to ethanol of 1:(0.5-2), such as 1:0.5, 1:0.6, 1:0.7, 1:1, 1:1.5, or 1:2.

[0032] The present invention will be described in detail below through embodiments.

[0033] In the following examples, the method for detecting the phenol content in (meth)acrylate samples is ultraviolet spectrophotometry, specifically: the quantitative analysis method employs a standard curve method. Taking hydroquinone as an example, firstly, a series of standard solutions of different concentrations are prepared using hydroquinone and (meth)acrylate. At a wavelength of 309 nm, the absorbance of each standard solution is measured. A standard curve is plotted with absorbance values ​​on the ordinate and the corresponding concentration values ​​on the abscissa. Finally, the absorbance value of the test sample solution is measured, and the corresponding concentration or content of the test sample solution is determined from the standard curve.

[0034] The single extraction phenol removal rate is calculated as follows: 100% × (hydroquinone content before extraction - hydroquinone content after extraction) / hydroquinone content before extraction.

[0035] The yield of methacrylate is calculated as 100% × mass of methacrylate after extraction / mass of methacrylate before extraction.

[0036] Example 1

[0037] The sample mass of lauryl methacrylate was 49.54 g, containing 2000 mg / kg of hydroquinone. 39.63 g of a methanol-water-water-soluble imidazoline solution (containing 70 wt% methanol, 27 wt% water, and 3 wt% water-soluble imidazoline) was added to the lauryl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 30 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component lauryl methacrylate. 48.90 g of the light component lauryl methacrylate was collected. After treatment, the hydroquinone content in the lauryl methacrylate was 120 mg / kg, the single-extraction phenol removal rate was 94.0%, and the lauryl methacrylate yield was 98.7%.

[0038] Example 2

[0039] The sample weight of decyl methacrylate was 50.01 g, containing 4000 mg / kg of 2,6-di-tert-butyl-p-cresol. 30.00 g of tetraethylene glycol was added to the decyl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 30°C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component decyl methacrylate. 49.77 g of the light component decyl methacrylate was collected. After treatment, the 2,6-di-tert-butyl-p-cresol content in the decyl methacrylate was 5 mg / kg, the single-extraction phenol removal rate was 99.9%, and the yield of decyl methacrylate was 99.5%.

[0040] Example 3

[0041] The butyl acrylate sample weighed 45.10 g, containing 500 mg / kg of resorcinol. 50.00 g of polyethylene glycol 200-1,2,4-triazole solution (containing 96 wt% polyethylene glycol 200 and 4 wt% 1,2,4-triazole solution) was added to the acrylate. The mixture was thoroughly mixed in a separatory funnel at 60 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component butyl acrylate. 44.49 g of the light component butyl acrylate was collected. After treatment, the resorcinol content in the butyl acrylate was 1 mg / kg, the single extraction phenol removal rate was 99.8%, and the butyl acrylate yield was 98.6%.

[0042] Example 4

[0043] The sample weight of hexadecyl methacrylate was 60.00 g, containing 2000 mg / kg of resorcinol. 60.00 g of an ethanol-n-hexanol-water-soluble imidazoline solution (containing 40 wt% n-hexanol, 54 wt% ethanol, and 6 wt% water-soluble imidazoline) was added to the hexadecyl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 40 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component hexadecyl methacrylate. 57.77 g of the light component hexadecyl methacrylate was collected. After treatment, the resorcinol content in the hexadecyl methacrylate was 32 mg / kg, the single-extraction phenol removal rate was 98.4%, and the hexadecyl methacrylate yield was 96.3%.

[0044] Example 5

[0045] The sample weight of lauryl methacrylate was 50.00 g, containing 2000 mg / kg of hydroquinone. 60.00 g of an ethanol-water-1,2,4-triazole solution (containing 40 wt% ethanol, 53 wt% water, and 7 wt% 1,2,4-triazole) was added to the lauryl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 50 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component lauryl methacrylate. 48.19 g of the light component lauryl methacrylate was collected. After treatment, the hydroquinone content in the lauryl methacrylate was 35 mg / kg, the single-extraction phenol removal rate was 98.3%, and the lauryl methacrylate yield was 96.38%. The heavy component extract phase could be used to recover ethanol and water by vacuum distillation.

[0046] Example 6

[0047] The sample weight of lauryl methacrylate was 50.00 g, containing 1500 mg / kg of hydroquinone. 30.00 g of ethylene glycol-1,2,4-triazole solution (containing 94 wt% ethylene glycol and 6 wt% 1,2,4-triazole) was added to the lauryl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 30 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component lauryl methacrylate. 49.51 g of the light component lauryl methacrylate was collected. After treatment, the hydroquinone content in the lauryl methacrylate was 2 mg / kg, the single-extraction phenol removal rate was 99.8%, and the yield of lauryl methacrylate was 99.0%.

[0048] Example 7

[0049] The procedure was carried out according to Example 6, except that ethylene glycol was used as the extractant. At 30°C, the mixture was thoroughly mixed in a separatory funnel and allowed to stand for phase separation to obtain a heavy component extract phase and a light component lauryl methacrylate. 49.50 g of the light component lauryl methacrylate was collected. After treatment, the hydroquinone content in the lauryl methacrylate was 46 mg / kg, the single-extraction dephenolization rate was 96.9%, and the yield of lauryl methacrylate was 99.0%.

[0050] Example 8

[0051] The procedure was carried out according to Example 1, except that the mass ratio of lauryl methacrylate to methanol-water-water-soluble imidazoline solution was 1:0.3. The mixture was thoroughly mixed in a separatory funnel at 30°C, and allowed to stand for phase separation to obtain the heavy component extract phase and the light component lauryl methacrylate. After treatment, the hydroquinone content in lauryl methacrylate was 433 mg / kg, the phenol removal rate after a single extraction was 78.4%, and the yield of lauryl methacrylate was 97.4%.

[0052] Example 9

[0053] The sample mass of lauryl methacrylate was 50.00 g, containing 2000 mg / kg of hydroquinone. 40.00 g of a tetraethylene glycol-water-soluble imidazoline solution (containing 97 wt% tetraethylene glycol and 3 wt% water-soluble imidazoline) was added to the lauryl methacrylate sample. The mixture was thoroughly mixed in a separatory funnel at 30 °C, and allowed to stand for phase separation, yielding a heavy component extract phase and a light component lauryl methacrylate. 49.18 g of the light component lauryl methacrylate was collected. After treatment, the hydroquinone content in the lauryl methacrylate was 5.4 mg / kg, the single-extraction phenol removal rate was 99.7%, and the yield of lauryl methacrylate was 98.36%.

[0054] Example 10

[0055] The method of Example 5 was followed, except that the extractant was an ethanol-n-hexanol-water-soluble imidazoline solution (containing 34 wt% n-hexanol, 60 wt% ethanol and 6 wt% water-soluble imidazoline). After treatment, the hydroquinone content in lauryl methacrylate was 32 mg / kg, the phenol removal rate of a single extraction was 98.4%, and 49.00 g of the light component lauryl methacrylate was collected, with a lauryl methacrylate yield of 98.0%.

[0056] Comparative Example 1

[0057] The sample weight of lauryl methacrylate was 60.00 g, containing 2000 mg / kg of resorcinol. 90.00 g of 5 wt% NaOH aqueous solution was added to the lauryl methacrylate sample. After stirring at 30 °C for 30 min and allowing to stand for phase separation, an aqueous solution containing phenol salts and 50.39 g of lauryl methacrylate were obtained. After treatment, the resorcinol content of lauryl methacrylate was 0 mg / L, the phenol removal rate of a single extraction was 100%, and the yield of lauryl methacrylate was 83.9%. The obtained heavy component, i.e., the aqueous solution containing phenol salts, could not be recovered, and its COD value was extremely high, making it very difficult to treat biochemically.

[0058] Comparative Example 2

[0059] The method was followed as in Example 1, except that tetradecyl alcohol-ethanol (mass ratio 8:2) was used as the extractant. The mixture was thoroughly mixed in a separatory funnel at 60°C, and allowed to stand for phase separation to obtain the heavy component extract phase and the light component lauryl methacrylate. After treatment, the hydroquinone content in the lauryl methacrylate was 850 mg / L, the phenol removal rate after a single extraction was 57.5%, and the yield of lauryl methacrylate was 92.1%.

[0060] Comparative Example 3

[0061] The method was followed according to Example 2, except that 1,2-decanediol was used as the extractant. The mixture was thoroughly mixed in a separatory funnel at 60°C, and allowed to stand for phase separation to obtain the heavy component extract phase and the light component decyl methacrylate. After treatment, the 2,6-di-tert-butyl-p-cresol content in decyl methacrylate was 864 mg / kg, the single-extraction phenol removal rate was 78.4%, and the yield of decyl methacrylate was 92.5%.

[0062] In Examples 1, 4, 5, 8, and 10 of this invention, the extractant used was a monohydric alcohol. A comparison of Examples 1 and 5 revealed that the mass ratio of monohydric alcohol to water affected the removal of phenols and the recovery of esters. Within the preferred range of this invention, a ratio that facilitated the removal of phenols and the recovery of esters was more favorable. A comparison of Examples 1 and 8 showed that the mass ratio of (meth)acrylate sample to extractant within the preferred range described in this invention was more conducive to the removal of phenols and the recovery of esters.

[0063] In Examples 2, 3, 6, 7, and 9 of this invention, polyols were used as extractants. Comparing Examples 2 and 9, it was found that when tetraethylene glycol was used as the extractant, superior results were achieved without introducing an extraction aid (especially when the sample to be treated was decyl methacrylate). Comparing Examples 6 and 7, it was found that when ethylene glycol was used as the extractant, adding a small amount of 1,2,4-triazole resulted in superior results (especially when the sample to be treated was lauryl methacrylate). Comparing Examples 1 and 9, it was found that the extraction effect of polyols was significantly better than that of monohydric alcohols.

[0064] As can be seen from the above examples and comparative results, when refining (meth)acrylates, using only the extractant and extraction conditions specified in this invention can effectively remove phenolic compounds from the (meth)acrylate sample, resulting in high extraction efficiency and a relatively high yield of (meth)acrylates. Furthermore, the extractant can be recycled, significantly reducing the emission of waste.

[0065] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for purifying (meth)acrylates, characterized in that, The method includes: mixing (meth)acrylate sample and extractant, extracting, and separating the phases to obtain a light phase and a heavy phase containing phenolic compounds; The extractant contains at least one of C1-C12 monohydric alcohols; or the extractant is at least one of polyhydric alcohols with a melting point of less than 40°C.

2. The method according to claim 1, wherein, In the (meth)acrylate sample, the number of carbon atoms from the structure of the alcohol is 1-20, preferably 4-18.

3. The method according to claim 1, wherein, The content of phenolic compounds in the (meth)acrylate sample is 5-9000 mg / kg, preferably 50-4000 mg / kg.

4. The method according to claim 1, wherein, The phenol is selected from monohydric phenols and / or polyhydric phenols.

5. The method according to claim 1 or 4, wherein, The phenol is selected from at least one of phenol, cresol, ethylphenol, dimethylphenol, 2,6-di-tert-butyl-p-cresol, naphthol, hydroquinone, and resorcinol.

6. The method according to claim 1, wherein, The mass ratio of (meth)acrylate sample to extractant is 1:(0.3-10).

7. The method according to claim 1 or 6, wherein, The mass ratio of (meth)acrylate sample to extractant was 1:(0.5-3).

8. The method according to claim 1 or 6, wherein, The extraction conditions include a temperature of 0-90℃, preferably 20-80℃.

9. The method according to any one of claims 1-4, wherein, The extractant is a polyol with a melting point of less than 35°C.

10. The method according to any one of claims 1-4, wherein, The polyol is selected from at least one of tetraethylene glycol, ethylene glycol, glycerol, and polyethylene glycol.

11. The method according to claim 1, wherein, The extractant also includes one or two of 1,2,4-triazole and water-soluble imidazoline; And / or, based on the total mass of the extractant, the mass content of the 1,2,4-triazole and / or water-soluble imidazoline is 2-10 wt%.

12. The method according to claim 1, wherein, The monohydric alcohol is selected from C1-C8 monohydric alcohols, preferably at least one of methanol, ethanol, propanol, butanol, pentanol, and hexanol.

13. The method according to claim 1, wherein, The extractant is a mixture of C1-C12 monohydric alcohols and water.

14. The method according to claim 13, wherein, The mass ratio of monohydric alcohol to water is (0.5-9):1, preferably (0.5-2.3):1.